Dabena



L. ALMAGIA AND E. GUERRESCH|.

ELECTRIC FURNACE. APIPLICATIQN, FILED SEPT-23, 1912.

Patented Apr. 13, 1920.

UNITED STATES PATENT OFFICE.

LEONE ALMAGIA, 0F CORNIGLIANO LIGURE, AND ERALDO GUERRESCHI, 0F SAMPIER-DARENA, ITALY, ASSIGNORS TO SOCIETA ANONIMA ITALIANA GIO. ANSALDO & (3.,

OF COBNIGLIAN LIGURE, ITALY.

ELECTRIC FURNACE.

Application filed September 23, 1918.

To all whom it may concern Be it known that we, LEONE ALMAGIA, engineer,subject of the King of Italy, and residing at Cornigliano Ligure, Italy,and ERALDo GUERRESOHI, engineer, subject of the King of Italy, andresiding at Sampierdarena, Italy, (the post-oflice address of both is:Societa Anoniina Italiana Gio. Ansaldo & (3., Cornigliano Ligure,Italy), have invented certain new and useful Improvements in ElectricFurnaces, of which the following is a specification.

This invention has for its object to provide an improved apparatus andan improved electric furnace whereby, with the aid of an electricalmachine, there can be obtained the control and the regulation of thedistribution of the heat in the various parts of the bath, and aninstantaneous automatic regulation of the short-circuit points, thusrendering it possible to supply the furnace with current fromany desireddistri bution cables, even if such cables are employed for lighting alarge district. This invention has also for its object to produce steelof superior quality.

One way of performing this invention is illustrated by way of example inthe accompanying drawings in which:

Figure 1 illustrates an apparatus for a furnace worked with tri-phasecurrent on the Heroult system. 7

Fig.2 is a diagram illustrating the voltages A, B, C between theelectrodes.

Fig. 3 illustrates an apparatus for a furnace worked with tri-phasecurrent on the Girod system.

Fig. 4 is a diagram illustrating the voltages:

AB=Bo= /5 being the voltages of each phase of the transformer.

Fig. 5 illustrates an apparatus for a furnace worked with tri-phasecurrent on the Ansaldo system.

Fig. 6 is a diagram illustrating the voltages: ABIBCZGA being thevoltages between the upper electrodes; ab=b0zoa being the voltages atthe lower electrodes; aA=bB=cC being the voltages of each phase of thetransformer.

Fig. 7 illustrates a furnace worked with Specification of LettersPatent.

Patented Apr. 13, 1920.

Serial No. 255,377.

tr -phase current on the Ansaldo system, with apparatus comprising anauxiliary transformer T Fig. 8 is a diagram showing the voltages withoutthe auxiliary transformer T F 1g. 9 is a diagram showing the volta eswith the transformer T ABzBOzaA being the voltages between the upperelectrodes; abzbczca being the voltages between the lower electrodes;aAzbB OC being the voltages of each of the phases of the transformer.

The improved furnace, provided with the device shown in Figs. 3 and 7,differs from the electric furnaces at present in use in this thatelectrodes connected to the beginning and to the end of the severalphases of a transformer (or alternator) are arranged upon the surface ofthe furnace and upon the bottom of the bath, the arrangement being suchthat the electric current is compelled to pass from an electrode toanother at the surface of the bath, and from an electrode at the bottomto another electrode at the bottom, and from an electrode at the surfaceto an electrode at the bottom through the bath, in such a manner thatthe bath is traversed by electric currents in all directions and is thusheated not only at the surface as in furnaces at present in use, but isheated both at the surface and in the interior and at the bottom.

hloreover, in the apparatus shown in Fig. 7 with the transformer T acontrol of the heat is obtained, which heat may be regulated at the willof the operator during the metallurgic process, and therefore during theperiod of fusion, and in case great variations of current are perceived,the heat can be concentrated upon the bottom of the furnace.

During the refining process, it will be advantageous to heat also theslag zone for effecting desulfuration and dephosphoration, and to modifyin other respects the heating of the bath according to the requirementsof the moment, and with relation to the metal which it is desired toproduce, by rendering the heating uniform throughout the mass of thebath during periods of time suggested by experience, thereby producing ametal of superior quality.

The transformer T besides permitting an ideal regulation of the heat,allows also Figs. 1, 2, 3 and 4;; if ,e represents the impedance of thesystem and Vs the voltage for the upper electrodes, there frequentlyoccurs a short-circuit current represented by the following formula:

wherein C is a constant.

In the furnace on the Ansaldo system illustrated in Figs. 5 and 6, withtheprinciples of the phases of transformer at the upper electrodes, wehave 'on the contrary:

i where Z is the impedance of the hearth .or

bottom of the furnace. v

From this it results that the short-circuit current is alreadyconsiderably smaller than in other furnaces; and is stillmore reduced inthe apparatus shown in Figs. 7, 8 and 9 comprising a transformer T thetransforming ratio of which is -0b7, so that we have now r V O V Bymaking ia variable, it is possible to vary the heating at any pointwhatever of the bath either near the bottom or near the surface. 7

In fact, if we limit by WVsthe Watts used at the surface, 2' the wattsused at the bottom,

we have:

W8 =f[ 1( l a =f[ 1( where the first function diminishes with theincrease of a or vice versa, the second ing li ise 1W 3 Wz': a constanth nc it l w that the transformer T limit the points of shortfcircuitwithin the d s r d l mits n ll ws f teg et ngth-e eat f th furnace.

Ha ng n wp rt eju erly de i and ascertained the "nature 10f our Saidinvenim nd t meml r in whi h th s me is to be performed we declare thatwhat we claim, is:

A device of the character described inu ng h ar h; a ov h r fo leleeformer conducting wires T between the transother conducting wiresbetween the transformer and the elec r d s th hearth, and a secondtransformer interposed in the st m t ned o duct ng Wi es a i seriestherewith.

In testimony whereof. we have hereunto ig ed ou ames in th p e n of twoWit- IIBSSGS. i

; LEONE ALMAGIA;

Witnesses:

CARLO LAR ZSI, AGOBTWO SALOMME- EB-ALDQ GUERBESCHI,

' ro esi h ea th an the cover, a trans r 7 former and the [electrodes inthe cover,

